The present invention relates generally to the insertion of prewound coils in magnetic cores such as dynamoelectric machine stator cores and more particularly to methods and apparatuses facilitating such insertion in cores having a relatively large stack height to bore diameter ratio.
A number of machines have been devised for inserting prewound coils as well as, optionally, insulating wedges into stator cores as illustrated by the Hill, U.S. Pat. No. 3,324,536 and Walker et al, U.S. Pat. No. 3,402,462. In devices of this type preformed coils, for example formed on winding machines of known types, are placed over appropriate tooling blades or fingers of the placer for subsequent insertion into a stator core. The coils for all of the poles of the dynamoelectric machine to be produced may be placed on the tooling blades and inserted simultaneously or individual coils may be positioned and inserted one at a time if desired. Similarly auxiliary or start windings may be inserted into the magnetic core either one pole at a time or simultaneously and in some instances both the main and start windings along with various insulating wedges may be inserted in stator cores by such machines. These insulators may be to separate one winding from another or to isolate the windings from the stator bore.
Stator cores having a large stack height to bore diameter ratio give rise to special problems in these known processes and devices. Such cores are encountered for example in the case of submersible pump motors where the motor is designed to be assembled with a pump and lowered down the casing of, for example, a water or oil well for the purpose of pumping fluid from that well. Such submersible pump motors will frequently have an axial length several times the stator bore diameter so that the coils for forming the windings are quite large and difficult to handle. This awkward aspect of the coils has frequently necessitated the insertion of coils for but a single pole during each pass of coil placer tooling of the above mentioned type.
A companion problem, in the assembly of relatively lengthy stators is that the insulating wedges are also quite long and difficult to load into the coil placing machine. A further related problem is that the reciprocating stroke of such a coil placing machine is relatively long and difficult to achieve.
Somewhat related to the above noted problems is that fact that the stack height or length of the stator core may vary from one motor design to another and the coil placing machine users, both original equipment manufacturers and ones where the rebuilding or rewinding of such motors takes place, desire that such machines may be relatively easily adapted to stator cores of various lengths.
The prior art technology for stack height adjustment is exemplified by the Walker et al, U.S. Pat. No. 4,156,964 and the serveral prior art techniques discussed therein. Again these known techniques are difficult to implement in machines for positioning coils in cores having a relatively large stack height to bore diameter ratio because of the substantial tooling lengths encountered in such machines.